Electrical winding construction



Jan. 21, 1964 W. T. SUTTON, JR

ELECTRICAL WINDING CONSTRUCTION Filed Aug. 4, 1958 INVENTOR 14/44 72:? Z'JurroMJ mmm ATTORNEYS United States Patent 3,119,084 ELECTRECAL WINDING CONSTRUCTION Walter T. utton, Jn, Lexington, Ky., assignor, by mesne assignments, to Nytronics, Inc., Phillipsburg, N.J., a corporation of New Jersey Filed Aug. 4, 1958, Ser. No. 752,863 3 Claims. (Cl. 336-92) My invention relates to an improved electrical coil and transformer construction rendering the same particularly useful in the automatic assembly of such cincuit components into circuit sub-assemblies, as into printed circuits. This application discloses improvements over and modifications of the various forms disclosed in Goldsmith Patent No. 2,836,805.

In the production of coils and transformers of the character indicated, particularly the variety in which the windings are received in a cup-shaped housing (that is, a housing having a coil-receiving space defined between inner and outer tubular members closed at one end and open at the other), and in which to meet the various circuit requirements of different customers it is necessary to provide various numbers of turns of one or more windings, it has been a very difficult problem to properly adapt a basic universal cup-shaped housing to properly receive a wide variety of coil sizes. For uniform electrical performance, and to meet the performance tolerances required by customers, it is necessary that the coil be accurately placed within the housing. This means accurate locating abutment of the coil within the housing against some positive reference to the bottom of the annular open space between inner and outer tubular members. In practice, this proper positioning has been accomplished by using various lengths of inserted plastic spacers, preliminarily assembled on the inner tubular member and serving as an abutment against which the coil winding may be driven. Unfortunately, however, such spacers may have burrs or for one reason or another may not seat accurately at the bottom of the coil-receiving space, so that inaccuracies in coil placement occur, with a resulting unnecessarily large number of rejects.

It is, accordingly, an object of the invention to provide an improved construction of the character indicated.

It is another object to provide an improved construction avoiding the disadvantages set forth above and yet lending itself to fabrication at substantially reduced cost.

It is a specific object to achieve the above objects with a construction in which the ends of the wire of the coil or coils are themselves the mounting prongs of strength adequate to provide the substantial mounting support for the circuit element.

It is in general an object to meet the above objects with an extremely rugged and simple device which can achieve or exceed the electrical performance of previous structures and which may be so rugged and permanent as to constitute a trouble-free component for the life of the circuit in which it is embodied.

Other objects and various further features of novelty and invention will be pointed out, or will occur to those skilled in the art, from a reading of the following specification in conjunction with the accompanying drawings. In said drawings, which show, for illustrative purposes only, preferred forms of the invention:

FIG. 1 is a longitudinal sectional view of a fully assembled transformer embodying features of the invention;

FIG. 2 is a sectional view, taken in the plane 22 of FIG. 1;

FIG. 3 is a view in perspective, partly broken away and shown in section, to reveal internal organization associated with the basic housing or capsule shape for the transformer of FIG. 1;

FIG. 4 is a view in elevation of the end of a tool for 3,119,084 Patented Jan. 21, 1964 "ice forming a suitable counterbore in the basic housing of FIG. 3;

FIG. 5 is a view in longitudinal section of the tool of FIG. 4; and

FIG. 6 is a view similar to FIG. 5 but showing an alternative tool.

Briefly stated, my invention contemplates application to the construction of coils, transformers, chokes and the like, for use in electronic circuit assemblies as, for example, in the video amplifier of a television set. The invention features integral formation of the turns of the electrical coil or coils with the mounting leads or prongs and, for this purpose, employs relatively heavy and stiff wire for the turns of the coil or coils. The assembly may be made rugged and adaptable to receive an adjustably positioned magnetic core by securing the same with a plastic bonding agent, such as an epoxy resin.

The particular feature of the present invention resides in the nature and construction of the housing or body member within which the integral coils are received and supported. In particular, the invention is concerned with means for accurately locating one or more coils, especially coils of different axial length, within the housing, the axial reference being so accurate that on a mass-production basis the rejection rate for a completed coil (by reason of inaccurate coil placement) may be reduced to virtually zero.

Referring to FIG. 1 of the drawings, my invention is shown in application to a transformer assembly in which inner and outer coils 1011 are supported concentrically on a tubular coil-form portion or stem 12 of a plastic body member, capsule or housing 13. The body member 13 includes at one end thereof an integral portion 14 which serves to close the annular coil-receiving space 15 defined between the inner tubular member or coil form 12 and an outer tubular member or skirt is. The windings 10-41 are each developed from relatively heavy and stiff insulated wire and are each shown as being a single layer of turns, the ends of which are so formed and trimmed as to project straight and axially beyond the axial confines of the coil and so as to similarly project beyond the open end of the coil-receiving space 15 when assembled to the body member 13. Heavy plastic-coated copper magnet wire or Copperweld (copper-sheathed steel wire) is well adapted to form each of the winding means lib-11.

The wire from which the windings 141-11 are formed is preferably so rugged that the projecting ends 1'718 of the coil 1% and 1-2.il of the coil 11 may serve as mounting pins for the finished structure, so that no soldering or other connection to separate pins is necessary to integrate the circuit component into its ultimate chassis. For convenience in mounting, the leads 1718 1}-20 may be nail-pointed by employing conventional machinery, but I indicate my preference that the projecting ends 17-13-19-2tl shall be merely dipped in a pool of solder and slowly raised so as to develop pointed soldered ends 17'-18-1929 in the manner of a stalactite, the solder being further desirable for ultimate simpler permanent assembly into a printed circuit. The leads 1718-192tl may project for different axial lengths, thereby providing unambiguous terminal identification.

To complete the basic assembly, a closure cap or cover member 21 is placed over the open end of the otherwise assembled transformer, and preferably in direct abutment with the adjacent end of the inner winding 10. Such cover 21 is formed with a plurality of angularly spaced recesses, as at 22 for the lead wire 19, and serving to locate all lead wires 17--18-19-2t) in angularly spaced relation about the axis of the assembly. Thus, although not shown, the cover 21 will be understood to have four such angularly spaced recesses, such as the recess 22. Cap 21 may be secured by bonding techniques or by local deformation, as by spun deformation of the projecting end of the coil form 12, indicated at 12'.

For unambiguous ultimate circuit orientation, I prefer that the housing 13 shall include an elongated key or projection 23 into which a locating projection or lobe (not shown) of the cap may be received, for accurate location of the leads 17-18-19-2tl with respect to the key 23, all as described in greater detail in copending Goldsmith application, Serial No. 715,377, filed February 14, 1958, now Patent Number 3,024,433. Such key means 23 renders the completed assembly adaptable to automatic handling machinery which may properly sense the orientation of the completed transformer to establish proper angular reference to the chassis to which the circuit components may be assembled.

I also indicate my preference that plastic bonding means such as an epoxy resin be employed to permanently secure the turns of the windings 19-11 to each other and to the coil-form portion 12. For clarity, such bonding is not shown in the present drawings, but full potting is illustrated in said Goldsmith patent and partial potting is illustrated in pending Goldsmith application, Serial No. 716,106, filed February 19, 1958, now abandoned.

In order to provide for adjustment of the electrical inductance of the coil lit, the bore 24 of the stem or coil form 12 may be ribbed or otherwise formed for selftapping accommodation of the threads of a ferrite or the like ferromagnetic core member 25, adjustably positionable along the length of the bore 24. I prefer that whatever the number of turns required in the ultimate leads specifietd for the transformer coils, these turns shall be concentrated to the maximum extent possible toward that axial end of the assembly which is closed by the cover 21. In other words, to the maximum extent possible, I prefer that a substantial axial length of the housing 13 shall be available for support of the core member 25 before substantial coupling in the electrical sense; this permits a maximum range of coupling adjustment, depending upon axial placement of the core member 25 in the bore 24.

In accordance with the invention, the body member or housing 13 is so formed initially as to inherently define inner axial-end limits or stops, unique for each of the two windings 111 to be accommodated for any particular transformer design. In the particular design shown, the inner coil ltl has a substantially greater number of turns than the outer coil 11, and therefore there is preferably a substantial axial offset between the inner limit or stop 26 for the inner coil and the outer limit or stop 27.

In accordance with the invention, the basic housing shape (see FIG. 3) is initially formed with a substantial excess of material, as at 28-29, in the annular space within which the coils 16-11 are to be received, and then, depending upon the particular coil sizes to be received, this excess material at 2829 is appropriately removed by means of a suitable tool, shown in one form in FIGS. 4 and 5, and in an alternative form in FIG. 6. Preferably, the excess material at 28-2 is provided as angularly spaced integral blocks or abutments formed into the initial moulding from which the basic housing shape 13 of FIG. 3 is made. This shape may extend integrally between the inner and outer walls 12-16, and integrally joined to the bottom 14, as shown.

The tools used, as for example in FIGS. 4 and 5, for removing parts of this excess material at 2829 comprise two axially spaced circular-saw or milling cutters 30-31 for preferably simultaneous boring and counterboring to precisely controlled depths, the offset D between cutting edges thereof being appropriate to the desired offset D between coils 1t911 to be inserted in the housing. Such offset will, of course, vary depending upon the transformer design required for ultimate circuit employment, and in FIG. 3 I suggest by doetted outline on the sectioned portions that the shoulder or stop 26 will be formed by the smaller-radius (further projected) saw 30, while the outer shoulder or stop 27 is formed by the largerradius (less projected) saw 31.

Because of the angular space initially formed between the portions 2829 of the housing, this angular space is available to receive, without interference, the offset inner lead 18 for the inner winding 10, said offset being great enough to bring the lead 18 radially outside not only the inner winding 10 but also the outer winding 11. Of course, it will be appreciated that the effective radial thickness of the saw element 30 is preferably slightly in excess of the wire diameter used for the inner coil 10, but this thickness should not be greatly in excess of such diameter because the stop 27 defined by the counterbore (cut by saw 31) must be available as a positive stop for the outer winding 11, which is carried by the inner winding 16.

The saw of FIG. 6 will be seen to provide cutting circles at 30 and at 31 corresponding to those of the tool of FIGS. 4 and 5. However, in FIG. 6, the tool comprises separate elements, the inner saw being formed on an inner tubular element 32, and the outer saw 31 being formed on an outer tubular element33. Said elements are telescopically related, and in order to adjust the axial offset between the cutting edges thereof, the securing means 34 coacts to hold a given adjustment of axial spacing. In the form shown, the shank 35, which may be received in a conventional drill chuck, is formed in the outer tubular member 33.

It will be seen that I have provided an improved transformer construction of the character indicated, wherein greater mass production of transformers can be achieved, with substantially improved electrical acceptability. A variety of transformer configurations may be made from any given housing shape by means of the method described herein, whereby a standardized housing shape is processed to receive any given coil configuration. In every case when the saw or milling tool is applied as a means to define the desired axial abutment for the respective transformer windings, it will be appreciated that the bore within the inner saw 30 (as at 36 in FIG. 5, and at 37 in FIG. 6) may be of such axial length and diameter as to be accurately guided on the coil-form or stem portion 12 during a cutting operation and to be axially limited by the bottom or shoulder of the bore, thereby accurately defining the stops at 26-27 in terms of the initial axial length of the stem 12.

While I have described the invention in detail for the preferred forms shown, it will be understood that modifications may be made within the scope of the invention as described in the claims which follow.

I claim:

1. In combination, a generally cup-shaped plastic container open at one end defining a top portion and closed at the other end defining a bottom portion and including an upstanding plastic inner tubular member, said container and tubular member being concentrically arranged and defining an annular space between the walls thereof, a stepped abutment, said abutment being positioned within said space adjacent the closed end thereof, a first electrical winding comprising a plurality of turns of rela tively heavy and stiff wire deriving concentric support directly from the inner tubular member and supported at its end portion by a first step of said stepped abutment in spaced relationship with said bottom portion, the inner axial end of said winding being formed in angularly offset relation with said abutment, and a second electrical winding comprising a plurality of turns of relatively heavy and stiff wire deriving concentric support directly from said first electrical winding and at its inner end by a second step of said stepped abutment, the ends of both said windings beingstraight and integrally formed to project of said wires being such that said projecting wire ends provide the substantial mounting support for said combination, and closure means securing said wire ends in angularly spaced relation and closing 011? the open end of said space.

2. In combination, a generally cup-shaped plastic container open at one end defining a top portion and closed at the other end defining a bottom portion and including an upstanding plastic inner tubular member, said container and tubular member being concentrically arranged and defining an annular space between the walls thereof, radially spaced stepped abutments, said abutments being positioned within said space adjacent the closed end thereof, a first electrical winding comprising a plurality of turns of relatively heavy and stiff wire deriving concentric support directly from the inner tubular member and supported at its end portion by a first step of said stepped abutments in spaced relationship with said bottom portion, the inner axial end of said winding being formed at an angular location intermediate two of said abutments, and a second electrical winding comprising a plurality of turns of relatively heavy and stiff wire deriving concentric support directly from said first electrical winding and limited axially by a second step of said abutments, the ends of said windings being straight and integrally formed to project axially beyond the axially open end of said body member and in angularly spaced relation, the weight and stiffness of said wires being such that said projecting wire ends provide the substantial mounting support for said combination, and closure means securing said wire ends in angularly spaced relation and closing off. the open end of said space.

3. An electrical coil housing comprising a generally cup-shaped plastic container open at one end and defining a top portion and closed at the other end defining a bottom portion and including an upstanding plastic inner tubular member, said container and tubular member being concentrically arranged and defining an annular space between the walls thereof, an abutment member formed integrally with at least a portion of said cup-shaped tubular body member intermediate the axial ends of said annular space and extending a substantial distance radially between said tubular members, said abutment member being provided with a stepped surface a portion of which is adapted to be preformed by automatically operable machinery to a first predetermined depth to receive in abutting relationship one end of a first electrical winding having a predetermined number of turns of relatively heavy and stiff wire, and said abutment member having another portion of said surface at a second predetermined depth to receive in abutting relationship one end of a second electrical winding having a predetermined number of turns of relatively heavy and stiff wire whereby said first and second electrical windings are axially positioned accurately and automatically relative to each other.

References Cited in the file of this patent UNITED STATES PATENTS 1,763,115 Wermine June 10, 1930 2,751,563 Willyard June 19, 1956 2,836,805 Goldsmith May 27, 1958 

1. IN COMBINATION, A GENERALLY CUP-SHAPED PLASTIC CONTAINER OPEN AT ONE END DEFINING A TOP PORTION AND CLOSED AT THE OTHER END DEFINING A BOTTOM PORTION AND INCLUDING AN UPSTANDING PLASTIC INNER TUBULAR MEMBER, SAID CONTAINER AND TUBULAR MEMBER BEING CONCENTRICALLY ARRANGED AND DEFINING AN ANNULAR SPACE BETWEEN THE WALLS THEREOF, A STEPPED ABUTMENT, SAID ABUTMENT BEING POSITIONED WITHIN SAID SPACE ADJACENT THE CLOSED END THEREOF, A FIRST ELECTRICAL WINDING COMPRISING A PLURALITY OF TURNS OF RELATIVELY HEAVY AND STIFF WIRE DERIVING CONCENTRIC SUPPORT DIRECTLY FROM THE INNER TUBULAR MEMBER AND SUPPORTED AT ITS END PORTION BY A FIRST STEP OF SAID STEPPED ABUTMENT IN SPACED RELATIONSHIP WITH SAID BOTTOM PORTION, THE INNER AXIAL END OF SAID WINDING BEING FORMED IN ANGULARLY OFFSET RELATION WITH SAID ABUTMENT, AND A SECOND ELECTRICAL WINDING COMPRISING A PLURALITY OF TURNS OF RELATIVELY HEAVY AND STIFF WIRE DERIVING CONCENTRIC SUPPORT DIRECTLY FROM SAID FIRST ELECTRICAL WINDING AN AT ITS INNER END BY A SECOND STEP OF SAID STEPPED ABUTMENT, THE ENDS OF BOTH SAID WINDINGS BEING STRAIGHT AND INTEGRALLY FORMED TO PROJECT AXIALLY BEYOUND THE AXIALLY OPEN END OF SAID BODY MEMBER AND IN ANGULARLY SPACED RELATION, THE WEIGHT AND STIFFNESS OF SAID WIRES BEING SUCH THAT SAID PROJECTING WIRE ENDS PROVIDE THE SUBSTANTIAL MOUNTING SUPPORT FOR SAID COMBINATION, AND CLOSURE MEANS SECURING SAID WIRE ENDS IN ANGULARLY SPACED RELATION AND CLOSING OFF THE OPEN END OF SAID SPACE. 